Indirect effects of Bax and Bak initiate the mitochondrial alterations that lead to cytochrome c release during arsenic trioxide-induced apoptosis.

Arsenic trioxide is a potent chemotherapeutic agent by virtue of its ability to selectively trigger apoptosis in tumor cells. Previous studies have demonstrated that arsenicals cause direct damage to mitochondria, but it is not clear that these effects initiate apoptosis. Here we used Bak-/- mouse liver mitochondria and virally immortalized Bax-/- Bak-/- mouse embryonic fibroblasts (MEFs) to investigate whether or not multidomain proapoptotic BCL-2 family proteins were required for arsenic-induced mitochondrial damage and cell death.

Epstein-Barr virus-encoded latent membrane protein 1 promotes stress-induced apoptosis upstream of caspase-2-dependent mitochondrial perturbation.

Previous studies have shown that Epstein-Barr virus (EBV)-encoded latent membrane protein 1 (LMP1) enhances etoposide-induced apoptosis in epithelial cells. Our study was undertaken to further dissect the modulation of tumor cell apoptosis by this viral protein. Using an inducible system of LMP1 expression in HeLa cells, we show herein that etoposide-triggered apoptosis, as evidenced by nuclear condensation and caspase-3 activation, is enhanced by LMP1.

VR-3848, a novel peptide derived from Euphobiaceae, induces mitochondria-dependent apoptosis in human leukemia cells.

VR-3848, a novel peptide derived from Euphobiaceae, is shown herein to induce apoptosis at nanomolar concentrations in the leukemic Jurkat cell line. Apoptosis was associated with activation of caspases, release of cytochrome c from mitochondria, fragmentation of nuclear DNA, and externalization of phosphatidylserine on the cell surface. Overexpression of mitochondria-targeted Bcl-2 abrogated VR-3848-induced killing in this model.

Phosphatidylserine exposure in Fas type I cells is mitochondria-dependent.

Previous studies have demonstrated that Fas-triggered activation of effector caspases and subsequent nuclear apoptosis either is mitochondria-independent (type I cells) or relies on mitochondrial amplification of the initial stimulus (type II cells). We show herein that Bcl-2 overexpression in a prototypic type I cell line (SKW6.4) promotes mitochondrial generation of ATP and blocks Fas-triggered plasma membrane externalization of phosphatidylserine (PS).